The present invention relates to a dropping device, preferably borne by a carrier aircraft, for distributing interference medium and especially electronic raspberry and interference medium with infrared (IR) signature, comprising a magazine provided with a rear feed-out opening viewed in the flight direction of the carrier aircraft and a number of packs of interference medium which are arranged one behind the other in the magazine and can be fed out on command, one-by-one through the feed-out opening, by a feed-out device forming part of the said magazine.
The basic principles for such a dropping device are previously known through, for example, SE B 8302508-0, whilst various types of interference medium packs suited thereto are described in EP 0 278 568 and SE B 505 070.
The dropping device described in SE B 8302508-0 is also therefore included, in which a magazine provided with a rear fed-out opening viewed in the flight direction of the carrier aircraft and within which packs of interference medium, arranged one behind the other, can be fed rearwards step-by-step towards and out of the feed-out opening by a feed ram driven by two parallel-running drive belts fastened to the front and rear edge of the ram, which drive belts firstly run along opposite sides of the magazine, on both sides of the packs of interference medium disposed therein, and secondly run back over diverting wheels disposed in the front and rear part respectively of the magazine, whereby they form closed loops. The said front diverting wheels are further joined by gearwheels one to another and to the motor which drives the whole of the feed-out system. The rear diverting wheels are then driven, in turn, by the feed belts. Level with the feed-out opening, special gearwheels are disposed on the same shafts as the rear diverting wheels and driven parallel with these, which special gearwheels, by interacting with toothed members on the packs, firstly, as long as they are stationary, act as stop catches for the rearmost packing and secondly, when rotated by a feed step, act as feed-out members for the same pack and finally, in connection with the feed-out of the rearmost pack, also separate the latter from the following pack with which in the original position it is meant to be coupled.
The above-described device has been widely used within a number of airforces throughout the world and has there proved both reliable and functional. A potential risk which has recently been observed is however that if both drive belts fail then the dropping device could in this realization end up releasing its entire load of packs of interference-suppression medium in a single sweep and this also without command. This theoretical possibility is in fact built into the system, since it is the gearwheels which act as both locks and feed-out members and these will be totally without both locking and driving function in the event of a double belt rupture. Like most other constructions which exist, neither is the device according to SE B 8302508-0 so good that it cannot also be improved and the present invention now relates to a modified variant of this device, which firstly provides a higher feed-out speed for the packs in question and secondly comprises a new indexing or drive function for the feed belts, i.e. de facto the feed ram and the packs of interference medium. In its new modified variant, the device also has the advantage that no feed-out whatsoever can occur unless the drive motor of the dropping device is working.
The higher feed-out speed for the packs of interference medium has been achieved according to the invention by the fact that the gearwheels of the older construction which co-rotate with the feed belts have been replaced by accelerator shafts or cam shafts which are arranged separately mounted in the side edges of the magazine feed-out opening and which, though parallel with the rear diverting wheel shafts of the drive belts, have had their motion stepped up by a number of whole multiples relative to the said diverting wheel shafts and are provided with the same number of brake and separation/acceleration cams which corresponds to that part of a turn by which it has to rotate in order to execute a feed-out of a pack of interference medium.
The accelerator shafts or cam shafts are configured with brake and separation/acceleration cams, which have the function firstly of blocking the feed-out of packs when no feed-out is to occur and secondly of exposing the feed-out opening when the feed-out is started and additionally of separating the outermost pack from its original detachable union with the next pack and finally of giving the outermost pack a final accelerating shove away from the dropping device.
As indicated previously, the feed-out device according to the invention also comprises a safety function which prevents any form of involuntary feed-out of interference medium packs after a drive belt rupture. This safety function has been achieved by the accelerator shafts in the flight direction of the carrier being made self-locking with respect to the interference medium packs. In the rest position of the device, the outermost interference medium pack in the feed-out direction will in fact always come to bear with its feed lugs disposed on both sides of the same against part-cylindrical locking surfaces on the accelerator shafts. These locking surfaces in turn constitute the outer periphery of one or other of the cams of the respective accelerator shaft. Between these part-cylindrical locking surfaces the accelerator shafts are then provided with their special feed grooves, which, when the accelerator shaft is rotated by the dedicated drive function, enter into engagement with the feed lug on the interference medium pack which is next in line to be fed out.
The dropping device according to the invention also requires a reliable indexing mechanism. The indexing mechanism which has now been developed for the dropping device according to the invention has a number of advantages which make it particularly well suited for use under the conditions for which the dropping device is intended and the special stresses to which it might herein be exposed, yet the indexing mechanism in question is also at the same time more universally applicable, for example in automatic packaging machines and other devices requiring a reliable, step-by-step and continually repeated feed function.
The indexing mechanism in question is thus dynamically balanced, which makes it independent of external vibrational and gravitational influence, which is essential when it is a question of parts belonging to modern combat aircraft. It further requires very little space to transmit high torques. It has high repeatability and, by virtue of the fact that indexing is effected through mechanical connection of in principle a single part, its indexing is independent of the friction for force/torque transmission.
The working of the indexing mechanism in question incorporates the feature that one or more turns of the rotation of an input shaft is/are relayed as indexing to a second output shaft. By choosing the number of turns which are required to be extracted from the output shaft, a number of different indexings can therefore be obtained. This gives the indexing mechanism in question a very high degree of flexibility.
The step-by-step feeding or indexing is thus achieved according to the invention by mechanical connection between a rotary input motor shaft and a driver, which is in turn is connected to a second output shaft, which is in line with the motor shaft but totally detached therefrom, and this second output shaft, following connection, imitating the rotation of the motor shaft for one or more full turns, wholly dependent upon the setting, so as thereafter to be disconnected and braked with immediate effect. According to a preferred embodiment of this system, the motor shaft is directly connected to a cylindrical drive drum arranged concentrically about the same, which drive drum is provided internally with a fluting in the form of grooves or cavities against which a driver which is adjustable between two different positions can be connected and disconnected. In its normal position, the driver, which is thus connected to the second output shaft, is held by an eccentric in engagement with a system-fixed stop lug. As soon as the eccentric is readjusted so that its influence upon the driver ceases, the driver will enter into engagement position against the flutes of the drive drum and will accompany the latter for one or more full turns so as, as soon as the latter re-establishes contact with the eccentric, to be disconnected from the drive drum and with its opposite end enter into engagement with the stop lug, whereupon the stop lug itself and the output shaft are simultaneously sharply braked. The sole control function which is required in this system, over and above the purely mechanical control of the connection and disconnection of the eccentric, is a delay between the activation command and the connection of the driver, which gives the motor time to reach full speed before the driver is coupled together with the drive drum. In those cases in which the drive motor is always switched on, there is obviously no need for any delay whatsoever. It is additionally required that the eccentric shall have been returned to its original position before the driver has completed the intended number of turns.
The driver which is characteristic of the device according to the invention is mounted tiltably about a crankshaft arranged parallel with the output shaft and somewhat eccentrically relative to the same, whilst the driver itself extends at a tangent transversely to this shaft, about which it is tiltable between its two working positions, i.e. alternatively with its end edge facing towards the rotational direction of the motor and in bearing contact against the fluted inner side of the drive drum or with its end edge facing in the rotational direction of the motor and in bearing contact against the fixedly disposed brake lug. In order to tilt over the driver from its position in bearing contact against the fluted inner side of the drive drum, in which position it can be held by, for example, a spring, into its other locked position in which its other end bears against the brake lug, the aforementioned mechanically adjustable eccentric, disposed in a fixed mounting directly beyond the outer edge of the drive drum, can preferably be used, by means of which the driver can be forced over into its other position. For this, the eccentric quite simply lifts the particular end of the driver out of its engagement with the fluting of the drive drum, whereupon the front end of the driver in the rotational direction encounters the stop lug. The fact that the eccentric has a fixedly disposed mounting and the drive drum and the driver, when the latter is connected, rotate about the shafts in question, means that the driver and the eccentric have one contact possibility per turn.
The invention has been defined in the subsequent patent claims and in which it should be noted that the indexing mechanism to which reference has previously been made can also be used in connection with other devices in which a similar step-by-step operation is desirable.